A method for reducing the resistivity of a carbon nanotube nonwoven sheet includes providing a carbon nanotube nonwoven sheet comprising a plurality of carbon nanotubes and applying pressure to the carbon nanotube nonwoven sheet to reduce air voids between carbon nanotubes within the carbon nanotube nonwoven sheet.

A structure includes a skin and a foam member. The foam member has a molded contour, the mold contour being configured to provide tooled surface for the skin. When the skin is a composite skin, the foam member provides support for the skin so that the skin can be cured under heat and pressure. A method of making the foam member for a foam stiffened structure includes creating a mold having an interior cavity which resembles a desired shape the foam member. A subsequent step involves introducing a foam mixture into the mold. Next, the foam mixture is allowed to polymerize so as to expand and distribute within the cavity of the mold. The method further includes selectively controlling a density of the foam member in the mold. The foam member is at least partially cured. The foam member is assembled with a skin to produce the foam stiffened structure.

A method for repairing the surface of rotor blades or aircraft wings, comprising (c) a composite substrate (1); and (d) a protection layer (2) having at least one area of at least partial damage, the method comprising: (vii) removing at least part of the damaged part of the protection tape (2); (viii) optionally, reconstructing the surface of damaged composite substrate (1); (ix) optionally, applying primer (6) solution to the surface of the composite substrate; (x) optionally, applying a polymer solution, preferably in at least one organic solvent; (xi) applying heat so as to heat the surface of the composite substrate; (xii) applying a polymer filament (7) onto the surface of the composite substrate so that the polymer filament melts and covers the damaged area.

A method of constructing a mandrel generally complementary to a spar cavity of a spar includes connecting a first component and a second component to form a central space there between and inserting a center component within the central space such that the center component retains the first component and second component in a desired position forming an outer surface of the mandrel which corresponds to an inner surface of the spar cavity.

An inboard bearing attachment for carrying centrifugal force (“CF”) loads in a rotor blade assembly of a rotorcraft includes a CF fitting having a curved surface and a shear bearing retainer aligned with the curved surface. A mounting flange connected to either the CF fitting or the shear bearing retainer is used to mount the inboard bearing attachment to a yoke.

A method is provided in one example embodiment and may include positioning at least one nozzle within a hollow portion of a rotor blade at a distance associated with a span of the rotor blade and providing, via the at least one nozzle, a liquid foam mixture in the hollow portion, wherein the liquid foam expands and becomes a solid foam material that fills the hollow portion of the rotor blade. Another method is provided in another example embodiment and may include providing a plurality of openings for a rotor blade that are positioned proximate to a hollow portion of the rotor blade and providing a liquid foam mixture in the hollow portion of the rotor blade through at least one opening of the rotor blade, wherein the liquid foam mixture expands and becomes a solid foam material that fills the hollow portion of the rotor blade.

Anti-icing stacks for protecting an aerodynamic surface are described. In some embodiments, an anti-icing stack includes an anti-icing layer, an elastomeric erosion protection layer, and an additional layer. The erosion protection layer is disposed between the anti-icing layer and the additional layer. The additional layer has a thickness greater than the thickness of the erosion protection layer and a tensile modulus of no more than the tensile modulus of the erosion protection layer. The additional layer may be a foam adhesive layer.

A method of fabricating a filler body for a blade of a rotor. In addition, such a method comprises a succession of steps of adding material layer by layer, each step consisting in making a new layer of material on a preceding layer of material made in the preceding step, at least one of the steps consisting in making an openwork layer of material presenting a plurality of openings, the succession of steps of adding material layer by layer generating openwork layers of material, each having a closed outline, the respective closed outlines of the openwork layers of material touching mutually in pairs and forming a closed envelope of the filler body for the blade.

Pre-impregnated composite material (prepreg) that can be cured/molded to form aerospace composite parts. The prepreg includes carbon reinforcing fibers and an uncured resin matrix. The resin matrix includes an epoxy resin component, polyethersulfone as a toughening agent, a thermoplastic particle component, a nanoparticle component and a curing agent.

In an implementation, a rotor blade (alternatively referred to herein as blade) for a helicopter or other aircraft may include an outer layer. The outer layer may define a cavity. The outer layer may at least partially correspond to an airfoil, e.g., a wing. One or more inserts may be included within the cavity and be encompassed thereby. The first insert may have a density of at least 0.6 pounds per cubic inch.